Re: instruction bundling (scheduling?)

On Apr 9, 11:29 pm, kphillips <kevin.phillip...@yahoo.com> wrote:
> One other query - I have no specific algorithms that cater for data
> prefetches. Since a load instruction take a huge amount of cycles
> (assuming the worst case scenario - memory), is it a good idea to
> issue advanced load instructions as early as possible? Then the
> latency for loads will be assumed for quite less .. hopefully it will
> work for most cases.


...and registers' live ranges will be quite longer, leading to higher
register pressure. You have to use a heuristic here.


Regarding scheduling vs register allocation -- I agree with Anton Ertl
that it is better to do scheduling first. For two reasons:
1. Usually, optimal, unhindered (by new dependencies introduced by
register allocation) scheduling is more important (no hard data here,
just my practical observations)
2. You have quite a few registers on Itanium (especially if you
allocate on single basic blocks level and thus, have all of the
registers free again at the start of each new block)


Andrey

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